The present invention relates to the field of aircraft tracking and identification. The present invention is specifically directed toward a technique for passively retrieving and correlating aircraft data from existing aircraft data sources.
The Federal Aviation Administration (FAA) requires all passenger carrying aircraft over 30 seats be equipped with so-called xe2x80x9cMode Sxe2x80x9d transponders. Mode S transponders are capable of transmitting a number (e.g., 25) of formats of coded data. This coded data includes such information as a unique 24-bit binary address for each aircraft.
The aircraft registration number may be derived from this 24-bit binary address. The coded Mode-S data also includes such information as aircraft altitude and is transmitted continuously throughout a flight at a minimum rate of 1 Hz (i.e., once per second). Coded Mode-S data may be collected passively without any connection to air traffic control equipment.
The FAA has endorsed the Aircraft Communications Addressing and Reporting System (ACARS) system, which uses various data link technologies including the VHF communication band, HF and SATCOM along with a ground station network to allow aircraft to transmit and receive messages of coded data. Many domestic and international carriers have equipped their aircraft with ACARS equipment.
ACARS equipment is capable of transmitting a number of types of coded data. ACARS currently uses frequency shift keying (FSK) as a modulation scheme, however, other modulation schemes including minimum shift keying (MSK) and time division multiple access (TDMA) are being evaluated for future improvement of ACARS. ACARS data includes such information as the aircraft registration number and airline flight identification number (flight number).
ACARS transmissions from a single aircraft may be sent at varying intervals from as little as no transmissions in a single flight to several transmissions per minute. ACARS transmissions may be collected passively without any connection to air traffic control equipment.
None of the currently used or planned Mode S downlink formats provides for the transmission of flight identification data. There are a number of methods including Automatic Dependent Surveillancexe2x80x94Broadcast (ADS-B) and multilateration which allow for the precise determination of aircraft location through the Mode S downlink formats on a frequent basis. ACARS transmissions, while capable of encoding aircraft position and altitude, are not typically used for position determination as the frequency of ACARS transmissions is too infrequent to allow one to accurately and timely determine the exact position of an aircraft.
The present invention includes hardware, software, and a methodology for correlating flight identification data with aircraft registration numbers. In a first embodiment featuring a 1090 MHz receiver, Mode S decoder, ACARS receiver, and ACARS decoder, aircraft registration numbers and other Mode S data are correlated with the current flight identification of an aircraft as well as other data provided from ACARS messages.
The present invention provides for linking (correlation) of flight identification data from ACARS messages with the data from Mode S transponder transmissions, which are more frequent and provide for real time position and altitude determination. The effect of which is to provide the same data as an air traffic controller would see on his or her screen without the need for active interrogation or connection to any Air Traffic Control equipment.